Peter knew about Ashley’s diet; he just didn’t particuarly care. Yes, he had swapped bodies with Ashley, so this was her body. But he was the one controlling it, and he wasn’t about to spend a week eating salads and wheatgrass. Sure, he’d imagine she’d be pissed when they swapped back and she found out about the entire pizza he ate in one sitting or the triple bacon cheeseburger he had in another. The weird thing was he didn’t have any problem scarfing it all down either. He figured she’d have a smaller stomach that would just get full. But he also knew he had his own brain that was used to eating big meals. He guessed the psychology won out over the physical space in her stomach. Or maybe she had just starved herself so much that her body was just happy to accept the gluttony for a change. Much like her diet, he didn’t particularly care the reasoning, he was just glad that despite the fact that he had her body, he didn’t really have to change his lifestyle.